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section .boot
bits 16
global boot
boot:
mov ax, 0x2401
int 0x15
mov ax, 0x3
int 0x10
mov [disk],dl
mov ah, 0x2 ;read sectors
mov al, 6 ;sectors to read
mov ch, 0 ;cylinder idx
mov dh, 0 ;head idx
mov cl, 2 ;sector idx
mov dl, [disk] ;disk idx
mov bx, copy_target;target pointer
int 0x13
cli
lgdt [gdt_pointer]
mov eax, cr0
or eax,0x1
mov cr0, eax
mov ax, DATA_SEG
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax
mov ss, ax
jmp CODE_SEG:boot2
gdt_start:
dq 0x0
gdt_code:
dw 0xFFFF
dw 0x0
db 0x0
db 10011010b
db 11001111b
db 0x0
gdt_data:
dw 0xFFFF
dw 0x0
db 0x0
db 10010010b
db 11001111b
db 0x0
gdt_end:
gdt_pointer:
dw gdt_end - gdt_start
dd gdt_start
disk:
db 0x0
CODE_SEG equ gdt_code - gdt_start
DATA_SEG equ gdt_data - gdt_start
times 510 - ($-$$) db 0
dw 0xaa55
copy_target:
bits 32
hello: db "Hello more than 512 bytes world!!",0
boot2:
mov esi,hello
mov ebx,0xb8000
.loop:
lodsb
or al,al
jz halt
or eax,0x0F00
mov word [ebx], ax
add ebx,2
jmp .loop
halt:
mov esp,kernel_stack_top
extern kmain
call kmain
cli
hlt
section .bss
align 4
kernel_stack_bottom: equ $
resb 16384 ; 16 KB
kernel_stack_top:And whenver I compile with nasm -f bin boot.asm -o boot.bin, I get boot.asm:77: error: binary output format does not support external referencesHi Mathi!
Thank you! Good to hear from you. I am old and tired, but in good health.
"main" and "printf" - without underscores - are for gnu C (Linux) too. Needed for 32 bit Windows. Watcom C wants "main_" and "printf_" etc. Go figure!
Nasm has "--prefix" and "--postfix" so we can add 'em from the command line...
Best,
Frank
Hi nohemon,
You are trying to compile a 32 bit example with 64 bit assembler/linker switches
If you want the 32 bit version. Your version should work , with proper assemble and linking commands.Code: [Select]global _main
;;assemble with > nasm -fwin32 hello32.asm
;;Link with > gcc -m32 -mconsole hello32.obj -o hello32.exe
extern _printf
section .text
_main:
push message
call _printf
add esp, 4
mov eax,0 ;;return code of our program
ret
message:
db 'Hello, World', 10, 0
If you intended to do this in 64 bit :
You may need to go through the below links for more info.
1)https://cs.lmu.edu/~ray/notes/nasmtutorial/
especially the 'Using Nasm in Windows' section. (Nice tutorial . Author might be in this forum)
2) x64 calling convention for Windows.
https://docs.microsoft.com/en-us/cpp/build/x64-calling-convention?view=vs-2019
1) What I noticed is that you need to lose the underscore (main instead of _main and printf instead of _printf) when linking with C libraries in 64 bit. (I dont' have a clear explanation for this).
2) for undefined reference to WinMain : you need to use console subsystem to tell the linker that this is a console application.
Link with : gcc -m64 -mconsole hello.obj -o hello.exeCode: [Select]
;;64 bit version.
;;assemble with > nasm -fwin64 hello.asm
;; link with > gcc -m64 -mconsole hello.obj -o hello.exe
global main
extern printf
section .text
main:
;---------
push rbp
mov rbp, rsp
;; reserve for local variables
;; 2 qwords for argc and argv
;; and 1 qword for return value
;; 1 more qword to align with 16 bits
sub rsp, 8*4
mov rcx, message
call printf
mov rax,0
add rsp,8*4 ;; deallocate local variables
pop rbp
ret
;---------
message:
db 'Hello, World', 13, 10, 0
extern _printf
section .text
_main:
push message
call _printf
add esp, 4
mov eax,0 ;;return code of our program
ret
message:
db 'Hello, World', 10, 0#include <stdio.h>
/* ---- data section ---- */
int i = 100; // We choose an integer to test
double d = -87.66; // really we'll a substraction
double l;
double res = 0;
/* .... text section ---- */
void main() {
l = i; // Convert INT i to DOUBLE l
res = l + d; // 'add' l +d and move it to res
/* ---- display res ---- */
printf("Result is: %g\n", res); // res = 12.34
}
;-------------------------------------------------------
; itof.asm
; Conversion INT to DOUBLE number & diplay it
; ------------------------------------------------------
; Assembly with GNU/Linux x80_86) & NASM compiler & GCC
; ------------------------------------------------------
; 1) Compile: nasm -f elf64 itof.asm
; 2) Link: gcc -no-pie itof.o -o itof
; 3) Run:./itof
; ------------------------------------------------------
bits 64
extern printf
section .data
i: dq 100 ; we'll test an int to add to a double
d: dq -87.66 ; really we'll rest d minus d
l: dq 0.0 ; l will become in the double value of i
fmt: db "Result is: %g", 10, 0
section .bss
res: resq 1 ; 64 bits for res
section .text
global main
main:
push rbp
.addition: ; int i --> float l ; res=l+d;
fild dword [i] ; conversion from an INT to DOUBLE \o/
fst qword [l] ; store the floating point (no pop)
fadd qword [d] ; floating add l (to st0)
fstp qword [res] ; store into res (pop flt pt stack)
.display:
mov rdi, fmt ; address of format string
movq xmm0, qword [res] ; res score
mov rax, 1 ; 1 argument to print
call printf ; calling printf
pop rbp
.exit: mov rax, 0
ret
global _main
;;assemble with > nasm -fwin32 hello32.asm
;;Link with > gcc -m32 -mconsole hello32.obj -o hello32.exe
extern _printf
section .text
_main:
push message
call _printf
add esp, 4
mov eax,0 ;;return code of our program
ret
message:
db 'Hello, World', 10, 0
;;64 bit version.
;;assemble with > nasm -fwin64 hello.asm
;; link with > gcc -m64 -mconsole hello.obj -o hello.exe
global main
extern printf
section .text
main:
;---------
push rbp
mov rbp, rsp
;; reserve for local variables
;; 2 qwords for argc and argv
;; and 1 qword for return value
;; 1 more qword to align with 16 bits
sub rsp, 8*4
mov rcx, message
call printf
mov rax,0
add rsp,8*4 ;; deallocate local variables
pop rbp
ret
;---------
message:
db 'Hello, World', 13, 10, 0
global _main
extern _printf
section .text
_main:
push message
call _printf
add esp, 4
ret
message:
db 'Hello, World', 10, 0